"Is it the prostate?", the four main cast members of Last Vegas ask each other at the merest phone call – rather poignantly in the case of Michael Douglas, who has only just recovered from a real-life cancer bout. If you imagined a fourth Hangover instalment about 35 years hence, it might look a lot like Jon Turteltaub's geriatric comedy, complete with a fatigued disinclination to raise hell in anything like the old ways. In truth, Vegas hotel suites don't have much to fear from this lot; the only substance in any real danger of being abused is Viagra.

Anyway, Douglas's character, Billy, calls round to invite three old partners in crime – Robert De Niro, Morgan Freeman, Kevin Kline – to his somewhat unexpected nuptials. The bride is half his age, so these pals refer to her as "the infant" more often than you might strictly imagine is funny. There's much bickering and wound-licking – De Niro's grumpy widower still nurses a grudge about Douglas's no-show at his wife's funeral, for reasons we easily figure out. And all of them, especially these two, are rather taken with the demure charms of a lounge singer, played by gorgeous-at-60 Mary Steenburgen, who seems a much more appropriate match for Douglas than his actual fiancée.

She's also more appropriate than the bootylicious parade of party girls besieging the foursome on all sides. In the film's least amiable sequence, they're called upon, practically dribbling, to judge a bikini competition. The script's on safer ground with an episode of broad role play, wherein they get their own back on a boorish adversary (Jerry Ferrara) by pretending to be a quartet of terrifying East Coast mobsters: a job at which Kline, who you can't imagine in any such role, is amusingly (and knowingly) poor. Compared with his lazy shtick in stuff like The Big Wedding, this uningratiating, often sour role is a much better chance for De Niro to deliver a real performance, too — he's playing the least likeable guy, but still manages to be best in show.

If only it were a show worth getting on the road at all. Good will is a currency any film can either profitably invest or just whip through, as this does, pouring it down the funnel of a harmlessly routine plot with life lessons just lying in wait to molest us. Given the colourful screen histories this cast invoke, their joint outing feels laden with pure, Viagra-defying anticlimax.